Scroll Wheel Test — Is Your Mouse Scroll Working?
The Scroll Wheel Test checks whether your mouse scroll wheel is working correctly, detects scroll direction (up/down), and measures your scroll speed in scrolls per second. It's useful for testing a new mouse, diagnosing scroll issues, or simply seeing how fast you can scroll.
What Does This Scroll Test Check?
- Scroll detection: Confirms your scroll wheel is registering events in the browser.
- Direction accuracy: Checks that up = up and down = down (some mice with inverted scroll wheels will show reversed directions).
- Smooth scrolling: Detects whether your mouse/OS is sending discrete steps (standard wheel) or continuous deltaY values (smooth scroll from trackpad, Mac Magic Mouse).
- Scroll speed: Counts total scroll events per second in timed mode.
Common Scroll Wheel Problems
If your scroll wheel test shows unexpected results:
- No scroll detected: Browser may have focus elsewhere. Click in the test zone first. Also check that the mouse USB/wireless connection is active.
- Reversed direction: Check your OS scroll direction settings. macOS has a "Natural" scrolling option that reverses the wheel direction.
- Skipping/erratic scrolls: Scroll wheel encoder may be dirty or worn. Try cleaning with compressed air.
- Double-scrolling: Some older mice register double events per click. This is a hardware issue (worn encoder).
Frequently Asked Questions
Use this scroll wheel test — if no events are detected when you scroll, or if the direction shown is wrong, your scroll wheel may have a hardware fault. Try the scroll on a different website too. If it fails everywhere, the mouse likely needs cleaning or replacement.
Scroll skipping is usually caused by a worn scroll encoder (the mechanical component that detects wheel movement). It can also be caused by dirty contacts. Cleaning the inside of the scroll wheel with isopropyl alcohol often fixes it.
Yes! Trackpad scrolling generates the same scroll events as a mouse wheel. The smooth scrolling indicator will show continuous scroll values (rather than discrete steps) when using a trackpad or Apple Magic Mouse.
The average person scrolls at 2–5 discrete scroll steps per second in casual use. In a dedicated speed test, 10–20 scrolls/second is achievable. The score isn't particularly meaningful for daily use — this test is primarily for diagnosing scroll wheel function.
Why Use JustDownSize Scroll Test?
Instantly shows each scroll event
Up/Down accuracy displayed live
Tells you if you have a trackpad/smooth scroll device
10-second timed scroll speed test
No download, no account
Detect skipping or reversed scroll